Apparatus for processing photographic material with radiation

ABSTRACT

Apparatus for receiving photographic materials exposed to radiation images and for processing resultant latent images. More specifically, one illustrative embodiment comprises a feed mechanism including a drive roller and first and second idler rollers for respectively inserting and withdrawing the photographically sensitized paper, a passageway for guiding the sensitized paper from and to the drive roller, and a single source of radiation. The single source of radiation serves the dual purpose of heating the sensitized paper to thereby retard the development of nonexposed portions of the sensitized material and, after heating, for developing the latent image by photolysis.

United States Patent AttorneysRobert W. Hampton and R. Lewis Gable [54] APPARATUS FOR PROCESSING PHOTOGRAPHIC fi ifif jggi i g ggg ABSTRACT: Apparatus for receiving photographic materials exposed to radiation images and for processing resultant latent images. More specifically, one illustrative embodiment comprises a feed mechanism including a drive roller and first and second idler rollers for respectively insertin the photographically sensitized paper, a pa g and withdrawing ssageway for guid- [51] Int Cl [50] FieldofSearch............................................

219/216, 388 ing the sensitized paper from and to the drive roller, and a sin- Rderences Cited gle source of radiation. The single source of radiation serves UNITED STATES PATENTS the dual purpose of heating the sensitized paper to thereby retard the development of nonexposed portions of the sensitized material and, after heating, for developing the latent image by photolysis.

2,921,513 1/1960 Frantz 355/107 3,183,819 5/1965 Gordon........................ 95/89 III/I l/IIIIII III Ill/I I PATENTED m2] 1am 3528 SHEET 1 [IF 2 WILLIAM S. OWEN GEORGE K. CZARNIKOW INVENTORS BY qmaiaz WMQM ATTORNEYS PATENTEDDEC21 1971 36221440 SHEET 2 BF 2 AC. WER

WILLIA OW GEOR ,G CZA KOW 1N VEN RS W/wu d4 WM 0 ATTORNEYS direct radiation of the desired APPARATUS FOR PROCESSING PI-IOTOGRAPHIC MATERIAL WITH RADIATION CROSS-REFERENCES TO RELATED APPLICATIONS Reference is made to commonly assigned copending U.S. patent application Ser. No. 625,590, entitled Radiation-Sensitive Silver Halide Systems, filed Mar. 24, 1967, now U.S. Pat. No. 3,447,927, name of Bacan and Barbier and U.S. patent application Ser. No. 481,918, entitled Photodevelopment of Silver Halide Printout Materials, filed Aug. 23, 1965, now U.S. Pat. No. 3,4 l 8, l 22,in the name of Colt.

BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to apparatus for developing photographic materials and, more specifically, to apparatus for the latensification of the exposed portions of the photographic materials while retarding the unexposed portions of the photographic materials.

2. Description of the Prior Art Materials are well known in the art which carry an emulsion that is sensitive to radiation and which may be developed by appropriate processes to render the image visible. Many photosensitive materials and emulsions are known in the art. One of the most well-known and widely used emulsions includes a silver halide compound typically disposed in a matrix of gelatin. The silver halide compound is normally present in the form of crystals.

In U.S. Pat. No. 3,143,940 and 3,144,332, there is described a process of latensification or development of a latent image in which a photographic emulsion of silver halide is processed by first subjecting the exposed emulsion to heat and then exposing the photographic material to radiation of a selected wavelength. The heating of the photographic emulsion is not believed to develop the latent image but rather serves to retard the development and to stabilize the nonexposed portion of the photographic emulsion. By a process of photolysis, the latent image is developed by the radiation in which the silver halide crystals decompose to produce a metalic silver deposit thereby providing a visible image. A theoretical explanation is provided in the introductory remarks of the above-identified patents of the physical nature of this process.

In the above-identified patents, there is shown apparatus for accomplishing the disclosed process in which separate elements are used to heat, and to expose the sensitized materials with radiation of the desired wavelength. Such apparatus requires separate means for energizing the heating elements and the source (e.g. lamps) of latensifying radiation. In addition, a portion of the energy radiated by these sources of radiation is dissipated or wasted in the form of heat.

Recently, it has been found that after development and photolysis by means of ultraviolet radiation, photolysis would continue under normal ofiice lighting conditions (e.g., in the order of approximately 1 foot candles) to an extent that the background of the exposed portion would be rendered unduly dark. To minimize the continued photolysis effect, it is suggested that the intensity of the ultraviolet source be greatly increased to thereby substantially reduce the objectional darkening of the background. As a byproduct of the considerable increase of ultraviolet energy output, heat is created which would have to be dissipated if this type of apparatus was to be used in an ofi'ice environment.

It is therefore an object of this invention to provide for the more efficient use of energy radiated in the form of light and heat.

It is a further object of this invention to develop latent images wherein a single source of radiation is used to both apply thermal energy upon the sensitized material and to wavelength onto the sensitive material.

It is a still further object of this invention to develop latent images wherein the continued photolysis efiect under normal lighting conditions is substantially retarded.

2 SUMMARY OF THE INVENTION In accordance with the teachings of this invention, these other objects and advantages are realized by developing apparatus including a feed mechanism having a drive roller associated with first and second idler rollers; a developing path between a first nip formed by the first idler roller and the drive roller, and a second nip formed by the second idler roller and the drive roller; and a single source of radiation. The single source of radiation serves the dual purpose of providing thermal energy to the sensitized materials to thereby retard development of the unexposed portions of the sensitized materials and also to direct radiation of the desired wavelength onto the sensitized material to effect the photolysis of the latent image.

As a further aspect of this invention, a heat-sensing element may be used to detect the temperature of the sensitized material and in turn to control the operation of means for dissipating thermal energy such as a fan.

The invention and its advantages will become apparent in the detailed description of the preferred embodiments presented below.

BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which:

FIG. 1 is a sectioned side view of apparatus for developing latent images in accordance with the teachings of this invention;

FIG. 2 is a sectioned view of the developing apparatus taken along line ll--ll of FIG. 1; and

FIG. 3 is a schematic diagram of the circuitry for energizing the motor and the source of radiation of the apparatus as shown in FIG. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and in particular to FIG. I, there is shown a processing apparatus 10 in accordance with the teachings of this invention which includes a housing 12 with first and second compartments l4 and 16 respectively. As will be explained in detail later, a sensitized material 25 such as a sheet of paper with an appropriate emulsion thereon is inserted into the processing apparatus 10 through an inlet passage 22 to be directed along a developing path 15. The material 25 has previously been exposed to a radiation image to form thereon a resultant latent image. As the material is directed along the path 15, the latent image is developed and finally the material 25 is withdrawn through an outlet passage 24. Along those portions of the developing path 15 in which the sensitized material 25 is to be heated, an insulating material 18 is disposed within the first compartment 14 to retard the escape of thermal energy. In one illustrative embodiment of this invention, it may be desired to cool the sensitized material 25 as a part of the developing cycle, and if so, the second compartment 16 is not filled with an insulating material but is rather provided with louvers 20 through which a cooling medium such as air may freely circulate to withdraw thermal energy from a heat sink 80.

The developing path 15 through the processing apparatus 10 is formed by a passage between an outer tubular member 26 and an inner tubular member 28 disposed concentrically with respect to the member 26. The outer tubular member 26 has extensions 30 and 32, which as shown in FIG. 1, extend substantially parallel to each other. Further, a guide member 34 is disposed between the extensions 30 and 32 and includes a pair of extensions 36 and 38 extending parallel with each other, and disposed in a parallel, spaced relationship with respect to the extensions 28 and 30, respectively, to form the inlet and outlet passages 22 and 24. As shown in FIG. 1, the sensitive material 25 is inserted into the processing apparatus 10 through the inlet passage 22 and is driven, as will be explained, through the inlet passage 22 between the guide member 34 and the extension 30, along the developing path formed between the relatively stationary, inner and outer tubular members 26 and 28, and finally withdrawn through the outlet passage 24 between the guide member 34 and the extension 32.

As will be explained later in greater detail, the sensitized material 25 is sequentially heated and then exposed to radiation of a given wavelength. Because the inner tubular member 28 is not rotated with respect to the outer tubular member 26, it becomes necessary to slide the sensitized material 25 along the path 15 between the inner and outer tubular members 26 and 28. Typically, the sheets of sensitized material 25 have a thickness in the order of 0.003 to 0.005 inch. It would be very difficult to machine or form the tubular members 26 and 28 with an accuracy sufircient to provide between the members 26 and 28 a uniform path of such a small thickness. Instead, a larger spacing in the order of a I/ 16 inch is provided between the members 26 and 28, and resilient means taking the form of a layer 58 of a resilient, low-friction material such as Teflon (a trademark of the Dupont Corporation for a fluorocarbon resin) and having a thickness generally corresponding to this spacing is secured upon the inner surface of the outer tubular member 26. In one particular illustrative embodiment, the layer 58 may take the form of a blanketlike material whose fibers are impregnated with Teflon so that the fibers resiliently hold the material 25 against the outer surface of the inner tubular member 28 to ensure an efficient thermal transfer between the material 25 and the members 28. It is further noted that the outer surface of the inner tubular member 28 may also be coated with a layer of teflon material to thereby further reduce the friction exerted upon the material 25.

The means for driving the sensitized material 25 along the path 15 includes a drive roller 44 which is rotated by a motor 68. More specifically, the rotational motion produced by the motor 68 is transmitted to the drive roller 44 through a pulley 72 directly coupled to the motor 68, a drivebelt 74, and a pulley 70 connected to the drive roller 44. The drive means further includes a pair of idler rollers 46 and 48 which are disposed respectively above and below the drive roller 44 as shown in FIG. 1 to insert and withdraw the sensitized material 25. The idler rollers 46 and 48 are pressed against the common drive roller 44 either by their own weight or in the alternative, by a pair of springs (not shown) resiliently biasing each end of the rollers toward the drive roller 44. Openings 40 and 41 are provided respectively in the extensions 30 and 36 to allow the rollers 46 and 44 to be pressed against the sensitized material 25; in a similar manner, openings 42 and 43 are provided in extension 38 and 32 to allow the rollers 44 and 48 to be pressed into contact with the sensitized material 25. Further, the motor 68 and the rollers 44, 46, and 48 are protected by a cover 78 secured to the housing 12 in any conventional manner. In operation, the roller 44 may be driven in a clockwise direction as shown in FIG. 1 by the motor 68 to thereby insert the material 25 along the path 15 (i.e., to move the material 25 to the right as seen in FIG. 1) and to act in conjunction with roller 48 to withdraw the sensitized material 25 (Le. direct the material 25 to the left as shown in FIG. 1).

The distance between the nip formed by the rollers 46 and 44, and the nip formed between the rollers 44 and 48 along the developing path 15 is a critical distance with regard to the corresponding dimension of the sensitized material 25. More particularly, the dimension of the sensitized material 25 must be greater than the above-described distance between the nip formed between rollers 46 and 45 and the nip formed between the rollers 44 and 48. If this condition is met, the sensitized material 25 will be engaged continuously and driven through the inlet passage 22, along the path 15 and through the outlet passage 24. On the other hand, if this relationship is not met and the distance between the nips of the rollers is greater than the length of the paper, a sheet of the sensitized material will be driven into the apparatus 10 and will not be able to be withdrawn because the leading edge of the sensitized material 25 will not be engaged by the rollers 44 and 48.

In order to process the latent image disposed upon the sensitized material 25, it is necessary to first expose the sensitized material to thermal energy of a prescribed intensity and then to expose the sensitized material 25 to radiation of a given wavelength. In accordance with the teachings of this invention, both of these steps are accomplished with but a single source 50 of radiation or energy. As shown in FIG. 2, the source 50 may take in one illustrative embodiment, the form of a mercury lamp of the type I-Il2T3 as manufactured by the General Electric Company, and disposed concentrically with respect to the inner and outer tubular members 28 and 26. A heat-absorbing surface 60 may be formed on the inner periphery of the inner tubular member 28 by illustratively blackening the inner, peripheral surface of the tubular member 28. Illustratively, the inner tubular member 28 may be made of a material such as aluminum which can be anodized to form the black heat-absorbing surface 60. As a result, the radiation emitted from the source 50 would be converted into thermal energy to heat the sensitized material 25 which as explained above has been pressed by the layer 58 into contact with the outer surface of the inner tubular member 28. An opening 66 is provided within the inner tubular member 28 so as to expose the sensitized material 25 to radiation from the source 50. As shown particularly in FIG. I, a layer 64 is disposed on the inner surface 60 of the inner tubular member 28 diagonally opposed from the opening 66 to provide a reflective surface for focusing the radiation emitted from the source 50 through the opening 66.

Dependent upon the photographic emulsion deposited upon the sensitized material 25, it may be desirable to cool the sensitized material 25 before it is exposed to radiation through the opening 66. As shown in FIG. 1, the heat sink is disposed within the second compartment 16 and, more particularly, is mounted upon the outer tubular member 26 within an opening 83 in the outer tubular member 26 to present a cooling surface 81 to the sensitized material 25. Further, the heat sink 80 may be provided with a plurality of fins 87 for dissipating the absorbed thermal energy as the cooling medium is allowed to circulate through the louvers 20 and within the compartment 16.

In certain applications, it may be desirable to maintain the intensity of the radiation directed onto the sensitized material 25 at a relatively fixed intensity to thereby photolize the latent image. In one particular application, approximately watts of ultraviolet radiation may be directed through the opening 66. A high proportion of the remaining energy emitted from the source 50 is absorbed by the inner tubular member 28. Typically, the source 50 of the type mentioned above may require a temperature in the order of 600 F. to operate efficiently. In addition the sensitized material 25 may not be heated above a certain value without scorching or burning the material. As a result, it is highly desirable to provide suitable means for controlling the temperature not only of the source 50 but also of the sensitized material 25. In one particular illustrative embodiment, a fan 54 is provided for circulating the cooling medium through the inner tubular member 28. As can be more clearly seen in FIG. 2, the fan 54 which is driven by a motor 56 impels a suitable cooling fluid such as air about the source 50 and against the inner surface of the inner tubular member 28. As shown in FIG. 1, a suitable temperature sensing means 62 such as a thermister of the type 6A5 lJl as manufactured by Femwald, Inc. is also disposed upon the inner surfaces 60. Further, a second fan (not shown) may be incorporated in the apparatus 10 at the other end of the tubular member 28 to assist the flow of air therethrough.

With reference to FIG. 3, there is shown an electrical circuit which is designed to control the operation of the fan motor 68 in response to a temperature-sensing means such as the thermister 62. A suitable source 124 of alternating current is applied through a pair of conductors 126 and 128 across the fan motor 68 by an armature switch 84, which is operated between an open and closed position by an armature coil 82. In turn, the armature coil 82 is energized by a switch means comprised of a triac 86 connected in series across the altemating power source 124 and a diac 88 connected to the gate of the triac 86. A resistor 90 and a capacitor 92 are connected in series across the triac 86 in order to prevent the premature firing of the triac 86 due to transients with short rise times appearing across the triac 86. The diac 88 is connected through a capacitor 94 to the conductor 128 and to the midpoint between diodes 100 and-114. The diodes 100 and 114 are connected through a resistor 96 to the conductor 126; the resistor 96 is of such a value to determine the potential at which the diac 88 and thus the triac 86 will be fired to their conductive states. Diode 100 is connected to the collector of a transistor 98 and also through a resistor 106 to the base of the transistor 98. Further, the emitter of transistor 98 is connected in series through a resistor 102 and the thermister 62 to the conductor 128. In a similar manner, the diode 114 is connected to the collector of a transistor 110 and through a resistor 112 to the base of the transistor 110. The bases of transistors 98 and 110 are respectively connected to the collectors of transistors 104 and 108. As shown in FIG. 3, the bases and emitters of transistors 104 and 108 are commonly connected. A resistor 116 is interconnected between the point of connection between the bases of transistors 1 04 and 108, and the point of connection between the emitters of transistors 98 and 110. Further, the point of connection between the bases of the transistors 104 and 108 is connected to a switch 76, which is disposable between first and second positions. When the switch 76 is disposed in its first position, the circuit of FIG. 3 is adjusted to detect a low range of temperatures in the order of approximately 200 to 230 F. More specifically, the switch 76 in its first position is connected in series through an adjustable resistor 118 and a resistor 117 to conductor 128. When the switch 76 is disposed in its second position, the circuit of FIG. 3 is adjusted to detect the high range of temperatures in the order of approximately 490 to 525 F. In the second position, the switch 76 is connected in series through an adjustable resistor I and a resistor 122 to the conductor 128. The resistors 118 and 120 are adjusted to precisely determine when the motor 68 will be turned on to cool the tubular members 26 and 28, and thereby the sensitized material 25.

Briefly, the operation of the circuit of FIG. 3 depends upon the change of resistance of the thermister 62 in response to the temperature within the tubular member 28. In the initial stage of operation of the processing apparatus 10, the temperature within the tubular member 28 is relatively low, e.g. room temperature, and the impedance presented to the circuit FIG. 3 by the thermister is relatively high. When a positive-going signal of the source 124 is connected through the resistor 96 to the diodes 100 and 1 14, the signal is blocked by the diode 1 l4 and is conducted by the forward-biased diode 100 to be applied through the resistor 106 to the base of transistor 98 thereby rendering transistor 98 conductive. As a result, a positive signal is applied through the resistor 106 to the base of the transistor 104, thereby tending to turn on the transistor 104 to a conductive state and applying a more negative signal to the base of the transistor 98. An equilibrium condition is achieved in which the transistor 98 is rendered partially conductive to allow only a relatively small current to be drawn therethrough. Thus the impedance presented between the point of interconnection of the diode 100 and the resistor 96, and conductor 128 through the path provided by the diode 100 and the transistor 98 is relatively high, and a positive potential is developed across the resistor 96 and the capacitor 94 to thereby fire the diac 88 and the triac 86. With the triac 86 in a conductive state, current is drawn through the solenoid coil 82 and the armature switch 84 is drawn through the solenoid coil 92 and the armature switch 84 is withdrawn and the motor 68 remains nonoperative.

As the temperature within the tubular member 28 rises, the resistance of the thermister 62 decreases. As a result, when the positive signal is applied through the resistor 96 and the diode 100, the transistor 98 is similarly biased to a conductive state, and as a result, a positive signal is applied to the base of transistor 104 thereby tending to bias the transistor 104 to its conductive state. However, with an increased temperature applied to the thermister 62, thermister 62 will present a lower resistance and a greater current will be drawn through the transistor 98, the resistor 102 and the thermister 62 to conductor 128. The potential applied through the resistance 116 to the base of transistor 104 will be reduced or become more negative thereby tending to render transistor 104 less conductive. In turn, the transistor 98 is turned on fully and the impedance between the point of interconnection of the diode and resistor 96 and ground is substantially reduced. When this state occurs, the potential applied across the capacitor 94 to the diac 88 is substantially lowered to the point where the potential is no longer sufficient to fire the diac 88. When the diac 88 is turned off, the triac 86 will likewise be switchedto its nonconductive state and no current will be drawn through the coil 82. The spring-biased armature switch 84 will be released thereby closing the circuit from the alternating current power source 124 through the motor 68. When the motor 68 is energized, the cooling medium will be directed through the inner tubular member 28 to thereby cool the sensitive material 25. It is particularly noted that the circuit shown in FIG. 3 is symmetric so that when the negative phase of the alternating signal derived from the source 124 is applied to the point of connection between the diodes 114 and l 10, a similar operation will take place with regard to the transistors 1 l0 and 108. As a result, when a high temperature decreases the impedance of the thermister 62, the transistor will be biased fully on thereby to prevent the firing of the diac 88 and the triac 86 with the result that the motor 68 is energized.

Thus there has been shown an apparatus for processing latent images in which but a single source of energy is used to effect the stabilization of the sensitized material by the application of thermal energy and in addition to expose the sensitized material to radiation of a given wavelength. As a result, the efliciency of this apparatus has been increased while eliminating an element normally incorporated in devices of the prior art.

Particular reference is made to above identified copending application Ser. No. 625,590 which describes in detail a particular embodiment of a process that could be used by the subject apparatus and to application Ser. No. 481,918 which sets out a particular example of a sensitized material that could be developed by the subject apparatus. Though such a sensitized material and process could be used with respect to the developing apparatus described herein, it is realized that other materials and processes could be used with equal facility in this apparatus.

The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention (as described hereinabove and as defined in the appended claims).

We claim:

ll. Apparatus for processing latent images recorded on sensitized material comprising:

means defining a developing path disposed between inlet and outlet openings, and including a tubular member; means for driving the sensitized material along said developing path; and

a source of radiation disposed within said tubular member,

said tubular member having an inner surface and a transmissive portion, at least a portion of said inner surface having the property of absorbing and converting radiation derived from said source into thermal energy for heating the sensitized material, said transmissive portion disposed to allow radiation derived from said source to be directed onto the sensitized material.

2. Apparatus as claimed in claim 1 further including means for cooling disposed along said developing path to remove thermal energy from the sensitized material prior to exposure of the sensitized material to radiation through said transmissive portion.

3. Apparatus as claimed in claim 2 wherein said means for cooling comprises a heat sink disposed adjacent said developing path.

4. Apparatus as claimed in claim 2, further including:

means for sensing the temperature of the sensitized material; and

means responsive to said means for sensing for directing a cooling fluid through said tubular member.

5. Apparatus as claimed in claim 2 wherein a second tubular member is disposed about said first-mentioned tubular member, said first and second tubular members defining at least a portion of said developing path, said first-mentioned tubular member and said second tubular member presenting respectively first and second surfaces to said developing path, at least one of said first and second surfaces having a sufficiently low coefiicient of friction to facilitate the passage of the sensitized material therebetween.

6. Apparatus as claimed in claim 5 wherein said second tubular member has means for defining an opening therein, said opening extending through said second surface at a point along said developing path prior to said transmissive portion, and there is further included a heat sink disposed within said opening of said second tubular member in intimate relation with said developing path.

7. Apparatus as claimed in claim 6 wherein said first-mentioned tubular member and said second tubular member are disposed within a housing, said housing being divided into at least first and second compartments, said first compartment being substantially filled with a heat-insulating medium, said second compartment enclosing said heat sink and having access means through said housing to allow the ambient environment to circulate therethrough.

8. Apparatus as claimed in claim 5 wherein said means for driving includes a drive roller, and first and second idler rollers forming with said drive roller respectively first and second nips, said first and second nips being disposed to drive the sensitized material along the developing path.

9. Apparatus as claimed in claim 8 wherein the sensitized material has a predetermined dimension along said developing path, said first-mentioned tubular member is disposed in a stationary relationship with respect to said second tubular member, and the distance between said first and second nips along said developing path is not greater than the predetermined dimension.

10. Apparatus as claimed in claim 1 further including resilient means for placing the sensitized material into intimate contact with at least a portion of said tubular member.

11. Apparatus as claimed in claim 1 further including:

a second tubular member disposed about said first mentioned tubular member, said first and second tubular members defining at least a portion of said developing path; and

resilient means disposed upon said second tubular member to press the sensitized material into intimate contact with said first tubular member.

12. Apparatus as claimed in claim 11 wherein said resilient means comprises a layer of felt coated with a material having such a coefficient of friction to facilitate the movement of the sensitized material along said developing path. 

1. Apparatus for processing latent images recorded on sensitized material comprising: means defining a developing path disposed between inlet and outlet openings, and including a tubular member; means for driving the sensitized material along said developing path; and a source of radiation disposed within said tubular member, said tubular member having an inner surface and a transmissive portion, at least a portion of said inner surface having the property of absorbing and converting radiation derived from said source into thermal energy for heating the sensitized material, said transmissive portion disposed to allow radiation derived from said source to be directed onto the sensitized material.
 2. Apparatus as claimed in claim 1 further including means for cooling disposed along said developing path to remove thermal energy from the sensitized material prior to exposure of the sensitized material to radiation through said transmissive portion.
 3. Apparatus as claimed in claim 2 wherein said means for cooling comprises a heat sink disposed adjacent said developing path.
 4. Apparatus as claimed in claim 2, further including: means for sensing the temperature of the sensitized material; and means responsive to said means for sensing for directing a cooling fluid through said tubular member.
 5. Apparatus as claimed in claim 2 wherein a second tubular member is disposed about said first-mentioned tubular member, said first and second tubular members defining at least a portion of said developing path, said first-mentioned tubular member and said second tubular member presenting respectively first and second surfaces to said developing path, at least one of said first and second surfaces having a sufficiently low coefficient of friction to facilitate the passage of the sensitized material therebetween.
 6. Apparatus as claimed in claim 5 wherein said second tubular member has means for defining an opening therein, said opening extending through said second surface at a point along said developing path prior to said transmissive portion, and therE is further included a heat sink disposed within said opening of said second tubular member in intimate relation with said developing path.
 7. Apparatus as claimed in claim 6 wherein said first-mentioned tubular member and said second tubular member are disposed within a housing, said housing being divided into at least first and second compartments, said first compartment being substantially filled with a heat-insulating medium, said second compartment enclosing said heat sink and having access means through said housing to allow the ambient environment to circulate therethrough.
 8. Apparatus as claimed in claim 5 wherein said means for driving includes a drive roller, and first and second idler rollers forming with said drive roller respectively first and second nips, said first and second nips being disposed to drive the sensitized material along the developing path.
 9. Apparatus as claimed in claim 8 wherein the sensitized material has a predetermined dimension along said developing path, said first-mentioned tubular member is disposed in a stationary relationship with respect to said second tubular member, and the distance between said first and second nips along said developing path is not greater than the predetermined dimension.
 10. Apparatus as claimed in claim 1 further including resilient means for placing the sensitized material into intimate contact with at least a portion of said tubular member.
 11. Apparatus as claimed in claim 1 further including: a second tubular member disposed about said first mentioned tubular member, said first and second tubular members defining at least a portion of said developing path; and resilient means disposed upon said second tubular member to press the sensitized material into intimate contact with said first tubular member.
 12. Apparatus as claimed in claim 11 wherein said resilient means comprises a layer of felt coated with a material having such a coefficient of friction to facilitate the movement of the sensitized material along said developing path. 